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Girl's Heart Beats Outside Her Chest: Rare Disorder Explained
A screengrab of a video showing a girl's rare condition that causes her heart to beat outside her chest.
Credit: RM Videos/YouTube

A girl's heart appears to beat literally outside of her chest in a recent video, but what causes this to happen?

The video, which was uploaded to YouTube in September, shows a young girl laughing as her heart beats outside of her chest, with just a thin layer of skin protecting the vital organ. The girl appears to be Virsaviya Borun, an 8-year-old who was born with a rare condition called pentalogy of Cantrell. (Borun's story first went viral in 2015.)

Pentalogy of Cantrell is an often-fatal disorder involving several birth defects in the chest and abdominal area, which can result in the heart being located just beneath a person's skin, as opposed to behind layers of bone, tissue and muscle. The disorder can include defects of the diaphragm (the muscle that separates the chest cavity from the abdomen and helps with breathing); the breastbone (sternum); the pericardium (the membrane that lines the heart); the abdominal wall and the heart itself, according to the National Organization for Rare Disorders (NORD).

(The term "penta" in the condition's name comes from the Greek word for "five," because the disorder can include up to five defects. However, most infants with the disorder do not have all five defects, NORD said.)

In the most severe form of pentalogy of Cantrell, people are born with their heart completely or partially displaced outside of the thoracic cavity. This cavity is the chamber that typically holds the heart, and it is protected by the rib cage. The intestines and abdominal organs of such people can also partially protrude outside their body through the belly button, NORD said. [Top 10 Amazing Facts About Your Heart]

Pentalogy of Cantrell is very rare, occurring in an estimated 5 people per 1 million live births, according to NORD.

Infants born with the condition often do not survive very long — a 2008 review study found that, out of 58 infants with pentalogy of Cantrell, 37 (64 percent) died within days of birth. In most cases, the condition is fatal without surgery to repair the defects, NORD said.

Borun is originally from Russia but now lives in Florida, according to local news station NBC 6 in South Florida. Borun and her mother came to the United States because a doctor at Boston Children's Hospital had agreed to treat her, but later made the decision not to perform surgery because Borun had high blood pressure in her pulmonary artery, which carries blood from the heart to the lungs. In 2015, Borun's mother started a fundraising campaign to raise money for her daughter's medical expenses, and raised more than $71,000, although the page is no longer accepting donations.

Original article on Live Science.